汽车实用英语

1、p82uniteighttext engine ignition systemall gasoline engines require some form of ignition system the purpose of this system isto。supply to the spark plugs ，within the engine combustion chambers ， high voltage surgesfurthermore， the ignition system must provide these surges or sparks to the correct c

2、ylinder 0fthe engine at the proper time in its operating cycle for most efficient combustionthe result ofthese sparks，of course，is ignition of the air fuel mixture within each 0f the combustionchambers.modern ignition systems operate from a battery conventional systems consist of the battery,ignitio

3、n coil ，distributor, condenser, ignition switch ，spark plugs，resistor and necessary low andhigh tension wiring the battery is the heat of the total electrical system in regard to the primary circuit ,itsfunction is to supply voltage and current flow to the primary windings of the ignition coilin ord

4、erto produce an electromagnetthe primary side of the ignition coil connects in series between the resistor and the breakerpoints the function of this coil when current passes through it is to create a very strongp83electromagnetic field. in other words, the coil becomes an electromagnet with n and s

5、 poles .themagnetic field from this coil, in turn, induces a voltage in the secondary windings that is necessaryto cause an arc at the spark plug gap.the secondary ignition circuit not only transforms the 6 or 12 volts of the battery to a voltagehigh enough to cause an arc at the spark plug but also

6、 delivers this high-voltage surge to the sparkplugs. the automotive battery supplies either 6 or 12 volts to the primary coil windings. but thevoltage necessary to jump across the spark plug air gap and ignite the air-fuel mixture can rangefrom 5 000 to 25 000 volts or more, depending upon the engin

7、es operating condition at any giventime.the ignition distributor has several functions. it opens and closes the primary ignition circuit.it distributes the high tension current to the respective cylinders of the engine. it also has amechanism that controls the point at which the breaker points open,

8、 thereby advancing or retardingthe spark in accordance with engine requirements.the distributor cap and rotor receive the high-voltage surge from the secondary coil windingsthrough a high-tension wire. this surge enters the distributor cap through its center terminal, knownas the coil tower to spark

9、 plug electrodes formed into the rim of the cap.the rotor itself mounts on the upper distributor shaft and rotates with it. as a result, therotorelectrode moves from one cap spark plug electrode to another, following the specific firing order ofthe engine.the purpose of the ignition condenser is to

10、reduce arcing at the breaker points, and prolongtheir life. most automotive condensers are formed from two thin foil strips, separated by severallayers of insulation. the insulating material is known as a dielectric and is usually paper or anysimilar nonconductive material.the spark plug provides th

11、e gap in the combustion chamber across which the high-tensionelectrical spark jumps to ignite the combustion charge.the purpose of the ignition switch is to connect and disconnect the ignition system from thebattery, so the engine can be started and stopped as desired.with the ignition switch on, an

12、d ignition distributor contacts closed; current will flow fromthe battery, through the primary winding of the ignition coil, to the distributor contact (breaker)points, to the ground connection and back to the battery.the current flowing through the primary winding of the ignition coil produces a ma

13、gneticfield in the coil, when the distributor contact points open (break), the magnetic field collapse andthe movement of the magnetic field induces current in the secondary winding. since there are manymore turns of wire in the secondary winding than there are in the primary winding, the voltage is

14、increased up to 20 000v.the distributor then directs this high voltage to the proper spark plug, where it jumps to thegap. the heat of the spark ignites the air-fuel mixture in the combustion chamber. the burning fuelexpands and forces the piston down. downward motion of the piston, in turn, rotates

15、 thecrankshaft.the ignition coil is a pulse transfomer designed to step up primary voltage (received fromp84electromagnetic field. in other words, the coil becomes an electromagnet with n and s poles .themagnetic field from this coil, in turn, induces a voltage in the secondary windings that is nece

16、ssaryto cause an arc at the spark plug gap.the secondary ignition circuit not only transforms the 6 or 12 volts of the battery to a voltagehigh enough to cause an arc at the spark plug but also delivers this high-voltage surge to the sparkplugs. the automotive battery supplies either 6 or 12 volts t

17、o the primary coil windings. but thevoltage necessary to jump across the spark plug air gap and ignite the air-fuel mixture can rangefrom 5 000 to 25 000 volts or more, depending upon the engines operating condition at any giventime.the ignition distributor has several functions. it opens and closes

18、 the primary ignition circuit.it distributes the high tension current to the respective cylinders of the engine. it also has amechanism that controls the point at which the breaker points open, thereby advancing or retardingthe spark in accordance with engine requirements.the distributorcap and roto

19、r receive the high-voltagesurge fromthe secondary coilwindingsthrough a high-tension wire. this surge enters the distributor cap through its center terminal, knownas the coil tower to spark plug electrodes formed into the rim of the cap.the rotor itself mounts on the upper distributor shaft and rota

20、tes with it. as a result, therotorelectrode moves from one cap spark plug electrode to another, following the specific firing order ofthe engine.the purpose of the ignition condenser is to reduce arcing at the breaker points, and prolongtheir life. most automotive condensers are formed from two thin

21、 foil strips, separated by severallayers of insulation. the insulating material is known as a dielectric and is usually paper or anysimilar nonconductive material.the spark plug provides the gap in the combustion chamber across which the high-tensionelectrical spark jumps to ignite the combustion ch

22、arge.the purpose of the ignition switch is to connect and disconnect the ignition system from thebattery, so the engine can be started and stopped as desired.with the ignition switch on, and ignition distributor contacts closed; current will flow fromthe battery, through the primary winding of the i

23、gnition coil, to the distributor contact (breaker)points, to the ground connection and back to the battery.the current flowing through the primary winding of the ignition coil produces a magneticfield in the coil, when the distributor contact points open (break), the magnetic field collapse andthe m

24、ovement of the magnetic field induces current in the secondary winding. since there are manymore turns of wire in the secondary winding than there are in the primary winding, the voltage isincreased up to 20 000v.the distributor then directs this high voltage to the proper spark plug, where it jumps

25、 to thegap. the heat of the spark ignites the air-fuel mixture in the combustion chamber. the burning fuelexpands and forces the piston down. downward motion of the piston, in turn, rotates thecrankshaft.the ignition coil is a pulse transfomer designed to step up primary voltage (received fromp85che

26、ckyourunderstandingi. give brief answer to the following questions.1. what is the function of the condenser in the distributor?2. what is the function of the series resistor?3. how does the high voltage induce in the secondary windings ?4. what does the ignition system consist of?ii. choose the corr

27、ect word to match the sentence.ignitioninducedistributorcondensercollapseelectrodecoronainsulation1._the material used for insulating2._to produce voltage by electromagnetic inductionp863_process which initiates the combustion of the compressed air-fuelmixture in the combustion chamber4_a faint glow

28、 enveloping the high-field electrode in a corona discharge，oftenaccompanied by streamers directed toward the low field electrode5_assembly which distributes the ignition voltage generated in the ignition coilto the spark plugs in the firing order of the engine6_to fall down or inward suddenly ； cave

29、 in7_capacitor for the contact breaker of a conventional distributor8_conductor which leads curlnt into a gas ，nquid or vacuum,such as those ina spark plug between which the spark passes to ignite the mixture fill in the table belowenglishhigh-tension wiringchinese初级绕组secondary windings串联spark plug磁

30、场pulse transformer断电器触点firing order接地iv translate the following sentences into eugnsh or chinese 1the distributor cap and rotor receive the high voltage surge from the secondary coilwindings through a high tension wire 2all gasoline engines require some form of ignition system3点火线圈由初级线圈、次级线圈和铁心组成。4点

31、火开关的作用是控制蓄电池与点火系统之间电路的通断。build up your v ocabularyi write down the words that the important abbreviation stands for1hal_ 热空气进气2hcv_ 温度调节阀3hepaf_ 高效微粒空气过滤器p874 hfrt_ 高频共振技术5 hfpr_ 燃油泵高速继电器6 hic_ 高温怠速空气补偿阀7 hlbl_ 前照灯光束高度校止8 hei_ 高能点火reading material electronic ignition systemthe function of the igniti

32、on system is to ignite the compressed air and fuel mixture， atthecorrect time ， and initiate its combustion in the spark ignition engine this is achieved bymeans ofbrief electrical arc discharge between the electrodes of the sparking plug in the early 1 970s many american vehicles began to install e

33、lectronic ignition systems，whichnow operate as part of an electronic engine-control system this action was necessary notonly tomeet stricter emission control standards but to increase the fuel economy of the vehicle allthefunctionthatusedtobedonemechanicallycannowbedonethroughelectronics centrifugal

34、 andvacuumadvance mechanisms in the distributor have been eliminated and ignition timingiscontrolled by the engine computer although the electronic system costs more to install than the standard system，the advantagesthat it offers more than the drawbacks of increased cost these advantages include：1g

35、reater available secondary voltage ， especially at high engine rpm2reliable and consistent system performance at any and all engine speeds3a potential for more responsive and variable ignition advance curves 4decreased maintenance cost of the systemp88to understand how an electronic system can provi

36、de all these advantages over thestandardsystem, lets review for a moment the inherent negative characteristics of the standard system. if yourecall, in order for a coil in the secondary voltage at all times, the contact points must remain closedfor a given period of time-the dwell period. as vehicle

37、 speed increases, the points open andclosemuch faster, and this reduces the effective time the points remain closed. consequently, there is areduction in the buildup time of the magnetic field around the primary coil, which is responsible forproducing secondary voltage. this characteristic of the st

38、andard system permits it to produce asubstantially large secondary voltage at lower engine speeds but a reduced voltage at highrpm.in addition, due to the fact that the contact points mechanically close and open (dueto theaction of a spring and the distributor cam), there is some arcing as the point

39、s open. this occursdespite a condenser in the circuit. this arcing results in point wear anti the requirement for periodicpoint replacement.in summation, standard ignition systems fail at high engine rpm to produce sufficientvoltagein order to prevent misfires. these misfires cause negative exhaust

40、emissions and decreasedeconomy. in addition, the standard system requires frequent service on its spark plugs, dueto lessavailable secondary voltage at high rpm, especially as the plugs air gap grows larger due tohighmileage. this, of course, increases emissions and reduces fuel economy.contact poin

41、ts require frequent service due to arcing. this arcing is a direct result ofhighprimary coil-induced voltage, which the condenser cannot handle at low engine speeds. as aresult,the point air gap increases so that the dwell is cut back. this reduction in dwell affects thesecondary coils ability to pr

42、oduce high voltage until it reaches a point where the entire systemmalfunctions, unless the contact points receive service.the electronic system, on the other hand, does not depend on mechanically operatedcontactpoints to open or close the primary coil circuit. as a result, the system can provide ov

43、erall highervoltages necessary to fire the leaner air-fuel mixtures on emission controlled engines and alsobridge enlarged air gaps due to plug wear. consequently, the electronic system reduces harmfulexhaust emissions, increases fuel economy, and lowers maintenance costs.the electronic ignition sys

44、tem (see figure 8.3) does not use the contact points as aswitchingdevice to open and close, the primary circuit. instead, the system uses an electronic switch intheform of one or more transistors to control primary current flow. these transistors and other parts ofthe solid-state control circuitry a

45、re inside a sealed control unit.since the early 1970s, a number of different types of electronic ignition systems havebeendesigned and produced by the automotive industry.the two general categories used to type these systems deal with the design of thetriggeringdevices and switching units. a trigger

46、ing device is necessary in any electronic system in order tosignal the switching unit to open and close the primary circuit. the two types of triggering devicesin general use are the contact points and the magnetic pulse. the two most common designsofswitching units are the inductive and the capacit

47、ive.many add-on and some of the early factories installed solid-state electronic ignitionsystemsadapted the control unit to the existing triggering device the ignition contact points. with thisp89arrangement, the system uses a conventional distributor with the original contact points, but the unitdo

48、es not require a condenser.in this contact-controlled system, a transistor assembly within the switching unit (theamplifier)takes over the traditional task of the contact points in controlling primary circuit current flow.inother words, the contact points in this electronic system act as an on-off s

49、witch for the emitter-basecircuit of the transistor handles the current flow of the primary-coil windings to ground whilethecontact points carry only about 1 ampere, depending on the make and model of the system.an electronic ignition system using a magnetic-pulse triggering device is similar to the

50、contactcontrolled type. however, when a magnetic pulse triggering is in the distributor, it switchesthetransistor on or off by means of an electrical charge induced through magnetism. since this systemhas no contact points at all, it is known as a breakerless electronic ignition system.p93unitninete

51、xtengine starting systemease of starting is one the major performance characteristics of internal combustion.to startsuch an engine, it is necessary to spin the engine crankshaft with sufficient speed for good mixingof air and fuel and adequate compression and ignition of the combustible charge. the

52、 minimumspeed with which the crankshaft of an engine should be rotated to ensure reliable starting oftheengine is referred to as the cranking speed. it depends on the engine type and starting conditions.the starting speed is 40 to 50 rpm for carburettor engines and 150 to 250 rpm fordieselengines. c

53、ranking the engine with a lower speed makes it more difficult for the engine to start, forin this case the charge has more time to escape through leaky joints and give off its heat ofcompression to the engine components, as a result of which both the pressure and temperature ofthe charge at the end of the compression stroke are reduced.the starting system provides the power to mm the internal combustion engine overuntil it canoperate under its own